diff options
Diffstat (limited to 'examples')
| -rw-r--r-- | examples/1_convolve_simple.cpp | 9 | ||||
| -rw-r--r-- | examples/2_convolve_overlap_save.cpp | 8 | ||||
| -rw-r--r-- | examples/3_fir.cpp | 8 | ||||
| -rw-r--r-- | examples/4_fir_pro.cpp | 10 | ||||
| -rw-r--r-- | examples/5_fir_differentiator.cpp | 8 | ||||
| -rw-r--r-- | examples/6_iir_test.cpp | 18 | ||||
| -rw-r--r-- | examples/7_iir_echo.cpp | 16 |
7 files changed, 48 insertions, 29 deletions
diff --git a/examples/1_convolve_simple.cpp b/examples/1_convolve_simple.cpp index 8de05d3..95877f1 100644 --- a/examples/1_convolve_simple.cpp +++ b/examples/1_convolve_simple.cpp @@ -7,10 +7,10 @@ * transient response is not calculated. */ -Sample *process_data(Samples samples) +Sample* process_data(Samples samples) { - // Define our output buffer. SIZE is the largest size of the 'samples' buffer. - static Sample buffer[samples.size()]; + // Define our output buffer. + static Samples buffer; // Define our filter constexpr unsigned int filter_size = 3; @@ -19,7 +19,8 @@ Sample *process_data(Samples samples) }; // Begin convolving: - for (int n = 0; n < samples.size() - (filter_size - 1); n++) { + // SIZE is the size of the sample buffer. + for (int n = 0; n < SIZE - (filter_size - 1); n++) { buffer[n] = 0; for (int k = 0; k < filter_size; k++) buffer[n] += samples[n + k] * filter[k]; diff --git a/examples/2_convolve_overlap_save.cpp b/examples/2_convolve_overlap_save.cpp index 57c020a..5651f3e 100644 --- a/examples/2_convolve_overlap_save.cpp +++ b/examples/2_convolve_overlap_save.cpp @@ -11,9 +11,9 @@ * computation. */ -Sample *process_data(Samples samples) +Sample* process_data(Samples samples) { - static Sample buffer[samples.size()]; + static Samples buffer; constexpr unsigned int filter_size = 3; float filter[filter_size] = { @@ -23,7 +23,7 @@ Sample *process_data(Samples samples) // Keep a buffer of extra samples for overlap-save static Sample prev[filter_size]; - for (int n = 0; n < samples.size(); n++) { + for (int n = 0; n < SIZE; n++) { buffer[n] = 0; for (int k = 0; k < filter_size; k++) { @@ -40,7 +40,7 @@ Sample *process_data(Samples samples) // Save samples for the next convolution run for (int i = 0; i < filter_size; i++) - prev[i] = samples[samples.size() - filter_size + i]; + prev[i] = samples[SIZE - filter_size + i]; return buffer; } diff --git a/examples/3_fir.cpp b/examples/3_fir.cpp index 3a68500..b6d8751 100644 --- a/examples/3_fir.cpp +++ b/examples/3_fir.cpp @@ -7,9 +7,9 @@ * within the available execution time. Samples are also normalized so that they center around zero. */ -Sample *process_data(Samples samples) +Sample* process_data(Samples samples) { - static Sample buffer[samples.size()]; + static Samples buffer; // Define the filter: constexpr unsigned int filter_size = 3; @@ -21,7 +21,7 @@ Sample *process_data(Samples samples) // Do an overlap-save convolution static Sample prev[filter_size]; - for (int n = 0; n < samples.size(); n++) { + for (int n = 0; n < SIZE; n++) { // Using a float variable for accumulation allows for better code optimization float v = 0; @@ -40,7 +40,7 @@ Sample *process_data(Samples samples) // Save samples for next convolution for (int i = 0; i < filter_size; i++) - prev[i] = samples[samples.size() - filter_size + i]; + prev[i] = samples[SIZE - filter_size + i]; return buffer; } diff --git a/examples/4_fir_pro.cpp b/examples/4_fir_pro.cpp index b1a6832..1771cd5 100644 --- a/examples/4_fir_pro.cpp +++ b/examples/4_fir_pro.cpp @@ -10,7 +10,7 @@ typedef struct static void arm_fir_f32(const arm_fir_instance_f32 * S, float32_t * pSrc, float32_t * pDst, uint32_t blockSize); -Sample *process_data(Samples samples) +Sample* process_data(Samples samples) { // 1. Define our array sizes (Be sure to set Run > Set buffer size... to below value!) constexpr unsigned int buffer_size = 500; @@ -34,18 +34,18 @@ Sample *process_data(Samples samples) static float working[buffer_size + filter_size]; // 3. Scale 0-4095 interger sample values to +/- 1.0 floats - for (unsigned int i = 0; i < samples.size(); i++) + for (unsigned int i = 0; i < SIZE; i++) input[i] = (samples[i] - 2048) / 2048.f; // 4. Compute the FIR arm_fir_instance_f32 fir { filter_size, working, filter }; - arm_fir_f32(&fir, input, output, samples.size()); + arm_fir_f32(&fir, input, output, SIZE); // 5. Convert float results back to 0-4095 range for output - for (unsigned int i = 0; i < samples.size(); i++) + for (unsigned int i = 0; i < SIZE; i++) samples[i] = output[i] * 2048.f + 2048; - return samples.data(); + return samples; } // Below taken from the CMSIS DSP Library (find it on GitHub) diff --git a/examples/5_fir_differentiator.cpp b/examples/5_fir_differentiator.cpp index 72415c6..1500dee 100644 --- a/examples/5_fir_differentiator.cpp +++ b/examples/5_fir_differentiator.cpp @@ -7,23 +7,23 @@ * A scaling factor is applied so that the output's form is more clearly visible. */ -Sample *process_data(Samples samples) +Sample* process_data(Samples samples) { constexpr int scaling_factor = 4; - static Sample output[samples.size()]; + static Samples output; static Sample prev = 2048; // Compute the first output value using the saved sample. output[0] = 2048 + ((samples[0] - prev) * scaling_factor); - for (unsigned int i = 1; i < samples.size(); i++) { + for (unsigned int i = 1; i < SIZE; i++) { // Take the rate of change and scale it. // 2048 is added as the output should be centered in the voltage range. output[i] = 2048 + ((samples[i] - samples[i - 1]) * scaling_factor); } // Save the last sample for the next iteration. - prev = samples[samples.size() - 1]; + prev = samples[SIZE - 1]; return output; } diff --git a/examples/6_iir_test.cpp b/examples/6_iir_test.cpp index 116a680..e0b266d 100644 --- a/examples/6_iir_test.cpp +++ b/examples/6_iir_test.cpp @@ -1,13 +1,23 @@ -Sample *process_data(Samples samples) +/** + * 6_iir_test.cpp + * Written by Clyne Sullivan. + * + * Implements a simple infinite impulse response (IIR) filter using an alpha + * parameter. + * To build upon this example, try setting `alpha` with a parameter knob: + * alpha = param1() / 4095.0 + */ + +Sample* process_data(Samples samples) { constexpr float alpha = 0.7; static Sample prev = 2048; samples[0] = (1 - alpha) * samples[0] + alpha * prev; - for (unsigned int i = 1; i < samples.size(); i++) + for (unsigned int i = 1; i < SIZE; i++) samples[i] = (1 - alpha) * samples[i] + alpha * samples[i - 1]; - prev = samples[samples.size() - 1]; + prev = samples[SIZE - 1]; - return samples.data(); + return samples; } diff --git a/examples/7_iir_echo.cpp b/examples/7_iir_echo.cpp index 57e5605..75bf56e 100644 --- a/examples/7_iir_echo.cpp +++ b/examples/7_iir_echo.cpp @@ -1,9 +1,17 @@ -Sample *process_data(Samples samples) +/** + * 7_iir_echo.cpp + * Written by Clyne Sullivan. + * + * This filter produces an echo of the given input. There are two parameters: + * alpha controls the feedback gain, and D controls the echo/delay length. + */ + +Sample* process_data(Samples samples) { constexpr float alpha = 0.75; constexpr unsigned int D = 100; - static Sample output[samples.size()]; + static Samples output; static Sample prev[D]; // prev[0] = output[0 - D] // Do calculations with previous output @@ -11,12 +19,12 @@ Sample *process_data(Samples samples) output[i] = samples[i] + alpha * (prev[i] - 2048); // Do calculations with current samples - for (unsigned int i = D; i < samples.size(); i++) + for (unsigned int i = D; i < SIZE; i++) output[i] = samples[i] + alpha * (output[i - D] - 2048); // Save outputs for next computation for (unsigned int i = 0; i < D; i++) - prev[i] = output[samples.size() - (D - i)]; + prev[i] = output[SIZE - (D - i)]; return output; } |